1. Field of the Invention
The invention is directed to a rotor wheel for a turbomachine, particularly a radial turbomachine, having a rotor wheel face and a shrink collar adjoining the rotor wheel face for shrinking onto a rotor of the turbomachine, a turbomachine having a rotor and a rotor wheel which is shrunk onto the rotor, and a method for producing a rotor wheel of this kind.
2. Description of Related Art
In turbomachines, rotor wheels convert energy of a fluid flowing through them and mechanical energy of a rotor supporting the rotor wheels into one another. In radial turbomachines, there is a flow through one or more rotor wheels transverse to the axis of rotation of the rotor for this purpose.
Rotor wheels are often axially secured to the rotor in frictional engagement by shrink fitting, i.e., an excess dimensioning of the outer diameter of the rotor relative to an inner diameter of the rotor wheel. To enlarge the contact surface of the shrink fit, known rotor wheels have shrink collars at one or both faces, i.e., axial extensions of the actual rotor wheel disk which have a smaller diameter. To ensure the safety-related axial fixing of the rotor wheels, the shrink collars can be additionally secured by shrink collar pins that penetrate aligned bore holes of the collar and rotor.
Owing to rotating speeds, which are very high at times, for example, in compressors, condensers, or turbines through which there is a flow of gas or vapor, the rotor wheels are acted upon by centrifugal forces which, among other things, lead to an expansion of the inner diameter of the rotor wheel and accordingly reduce the normal tensions applied by the shrink fit and, along with these normal tensions, the axially fixing frictional engagement. In so doing, shrink collar pins can be disadvantageously subjected to bending stresses or shear stresses and loaded by radial micromovements. Impaired operation, wear, or even failure of the turbomachine can result in both cases.